[S-SS05] Induced and Triggered Seismicity

[SSS05-P05] Seismicity monitoring and magnitude estimations with long-range DAS systems

*Martin Horst Karrenbach¹, Steve Cole¹ (1.OptaSense)

Keywords:Distributed Fiber-optic Sensing, seismicity, earthquake

Over the last several years the use of distributed fiber-optic sensing has increased for the purpose of earthquake and induced monitoring. Current state-of-the-art DAS systems interrogate up to 100km and are deployed on land and on the sea floor. We analyze a set of earthquakes recorded on a terrestrial telecom fiber in the vicinity of the Long Valley Caldera of the Western United States. Seismic events that are listed in official catalogues are also detected on the distributed fiber-optic sensing array, there is a set of small magnitude events that have been only detected on the fiber-optic data. The magnitudes estimated from the DAS system correlate with the official catalog magnitudes. The additionally detected small magnitude events fall below the catalog’s magnitude threshold and are located within 10km of the sensing array. This novel data set contains events within local magnitude range from -1.3 to 2.6. The large-aperture and the fine spatial sampling provided by the sensing array allows us to focus on the high signal-to-noise segments. Subarray processing further improves the signal quality, which is important for accurate magnitude estimations.